/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/VoiceInterface.h
Checks that a unique player id is on the specified user's mute list
true if the specified user is muted, false otherwise
bool IsMuted ( uint32 LocalUserNum, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & UniqueId ) const